1. Field of the Invention
The present invention relates to a base plate for foundation used as a member for a method for ventilating a place under the floor in a structure, especially in a housing and relates to a foundation utilizing the same.
2. Prior Art
With regard to the effect of ventilating a place under the floor of a wooden house constructed by a mat foundation manner, it has been proven that the foundation packing method is highly effective for preventing the timber from being decayed in comparison with a manner of the ventilation through a ventilation hole and, thus, the technologies for a base plates for foundation in the foundation packing method have been developed. The term "foundation packing method" used herein means a method for inserting a base plate for foundation between a mat foundation and a wooden sill.
The foundation packing method is a method in which a base plate for foundation is provided between a mat foundation made of concrete and a wooden sill placed on the mat foundation. In this method, the ventilation of a place under the floor is carried out through dehumidification grooves placed on the base plate for foundation and through gaps formed by the right and left sides of the base plates, a mat foundation residing at a lower portion, and a wooden sill residing at an upper portion. In comparison with the ventilation through the ventilation holes, generally produced by hallowing out a foundation, the foundation packing method has the merits that there is no lacking in the section at the rise of the foundation, there is no need of a desiccant sheet because the sill is not in contact with the foundation, narrow portions, such as corners, can be ventilated, ventilation means can be placed at portions near the front door and terrace where the provision of the ventilation hole is not preferable in terms of the design, and the like. The base plate for foundation used for such a foundation packing method requires considerable compression strength, considerable weatherability, considerable dehumidification property, and the like.
Japanese examined patent application 55-40734 discloses a base plate for foundation composed of a plastic composite. The base plate for foundation disclosed therein is a board having a rectangle shape as a whole, and possesses grooves on the top and bottom surfaces for the purpose of the stabilization and of the ventilation and drainage, etc. Optionally the base plate for foundation may possess mortises and dovetail grooves for jointing two or more base plates for foundation at the forward and backward portions, and mortises and dovetail grooves for rectangularly jointing them at the side portions. Moreover, it also possesses a long pore for penetrating a bolt for fixing the wooden sill set on the mat foundation.
However, the base plate for foundation described above has the problems as follows:
(1) The base plate for foundation is desirable to be placed under a pillar C in the case of the conventional frame work as shown in FIG. 5, or placed under a vertical frame T in the case of the wood frame construction as shown in FIG. 6. However, when the base plates for foundation having a rectangle shape as a whole as in the case of the conventional plates are used so that each of the long sides of the base plate for foundation is arranged to be in consistence with the axis of the mat foundation and the wooden sill, the gaps formed by the base plates for foundation residing at the right and left positions, the mat foundation D and the wooden sill K, i.e., the area of the projecting chart of the open hole for ventilating a place under the floor, is decreased. Especially, in the case of frame work method, which must use a large number of the base plates for foundation, the problem associated with decrease in a ventilation effect becomes significant. For this reason, the effect of the ventilation of a place under the floor is decreased. This is overcome by decreasing the area of projection chart of the base plate for foundation, but when it is excessively decreased, the capability to support a load is unduly decreased.
(2) Since the conventional base plate for foundation possesses a long pore for penetrating an anchor bolt for fixing the wooden sill D on the mat foundation K, even if the anchor bolt is somewhat deviated from the correct position, the application can be done without any problem. However, the long pore disclosed therein, which is linear, is not applicable except for the deviation of the position only in one direction.
(3) The conventional base plate for foundation has grooves for ventilation and dehumidification on both of the top and bottom surfaces thereof, and the direction of each groove is in consistence with the lengthwise direction of the base plate for foundation. The air for ventilation and dehumidification, therefore, only flows in one direction, and thus, it cannot be said that the base plate for foundation is of effective ventilation performance. Furthermore, since the grooves are provided on both of the top and bottom surfaces, the area in contact with the mat foundation and the wooden sill is small, resulting in the problem associated with the capability to support a load and slip resistance. This is significant when the total size of the base plate for foundation is decreased.
(4) Since the conventional base plate for foundation possesses grooves for ventilation and dehumidification on both of the top and bottom surfaces thereof and is composed of a plastic composite, the surface thereof easily slips. In the case of using this plate, the foundation of the housing becomes unstable.
(5) In the course of the production of the conventional base plate for foundation, the mold release is carried out with clamping the ends of the base plate for foundation after the injection molding, the base plate for foundation itself is easily deformed, causing the problem to have an adverse influence upon the quality thereof in some extents.